Dear Famis,

I will be glad to help you out. Please send this request to my email address.

Regards,

A. T. Agarwal

Consultant

Pneumatic Conveying Technologies

polypcc@aol.com

Ph and Fax: 304 346 5125 ■

RE Level switch:

Check the orientation of the gap in the forks is in line with the product/air flow this may help a lot. Alternatively if build up between the forks is the cause of the problem, we also manufacture a vibrating rod type device where orientation is not important.

If the product is adhereing to whatever device you use, then a non contact system could also be used, such as a microwave barrier (needs non conductive windows either side of pipe) or nucleonic switch (will work through almost any pipe and process material)

Thanks and Regards

Doug

www.vegacontrols.co.uk

Attachments

vib 61 (JPG)

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depending on the product consistency, the constant vibration of some tuning fork has been known to create small air pockets giving false signals. Most capacitance probes should avoid this problem. Other problems with pneumatic conveying systems is the product is aerated. when the high level is triggered the air is switched off and the product settles. You then find the silo is only half full. So when you choose a capacitance probe make sure it has the ability to ignore air/product mixtures and switch in the product only to maximise the fill capability.

john.slevin@hawker-electronics.co.uk ■

We got best results by using Vega-vibrating full signals, even for light and slighty humid ash from carbidge combustion by using VEGAVIB 51 indicator vibrating intesity can be adjusted.

www.intec-kohler.ch ■

can you please attach a drawing of the switch mounting?

How is it attached to the bin and where.

second what is the rest angle of your material .

third what is your materials density.

also if you can attach the sensor specs.

We might be able to help you out , use the same equipment .

Regards

marco ■

A good book to get you involved in the field can be Klinzing, Marcus Rizc Pneumatic Conveying Technology, or something like that , try s asearc with Roy Marcus as author and then Jorge Klinzing they are prolifiv writers I am sure you will find what you need there.

Regards

Marco ■

Dear Famis,

I assume you have a dilute phase system with a rotary valve. If it is, you should have the following interlocks and controls as a minimum:

1. Run rotary valve only if the blower has been running for a few minutes with an empty line.

2. During operation, if the blower discharge pressure is too high, rotary valve shuts down automatically and the blower continues to run for a few minutes. This is done so that the line gets cleared-up and the pressure drop comes down to normal.

3. If blower pressure drops to normal, rotary valve starts automatically.

4. If the blower pressure does not drop to normal, rotary valve does not re-start and a "system down" alarm comes on.

Regards,

A. T. Agarwal

Consulting Engineer

Pneumatic Conveying Technologies

polypcc@aol.com

Ph and Fax:304 346 5125 ■

Try reading Klinzing Marcus and Risk book on pneumatic conveying . There is a section on instrumentation.

I have had also problems with vibrating levell sensors and capacitance , Vibrating sensor will work well if properly located , we have a redundant loop with the dosiffier turn counter and time , in some plants , we installed radiation levell sensors as the product (metalic particles) was hot. there was some initial problem with the location of the source.

By the way cant you eliminate the sensors ?

there are valves available that will work fine with a static column, of solids trough them.

try purging your pressure differential lines before taking a reading.

Regards

Marco

marco ■